The present invention relates to a small-sized opening and closing device suitable for use especially with a portable telephone having an opening and closing mechanism.
Conventionally, a portable telephone where a transmitter section and a receiver section, or a keyboard side and a display side, thereof are mounted separately on a fixed side body and a movable side body respectively to be folded in two and opened and closed relative to each other, is known, and for this purpose, such an opening and closing device is known as shown, for example, in Japanese Patent Laid-open No. 8-125725, wherein a torsion spring wound spirally around a shaft is interposed resiliently between a mounting portion of the fixed side body and a mounting portion of the movable side body connected with each other via the shaft so as to be folded in two freely, and an arresting means for engaging one end portion of the torsion spring with the mounting portion of the movable side body only within a predetermined opening angle of the receiver section, is provided between the mounting portion of the fixed side body and the mounting portion of the movable side body while a cam mechanism is provided between the mounting portion of the fixed side body and the mounting portion of the movable side body, whereby the cam mechanism is operated by pushing a push-button disposed in an axial direction of the mounting portion of the fixed side body to rotate the receiver section to the position in which the arresting means arrests one end portion of the torsion spring, and wherein a locking means is provided for releasing the engagement of the movable side body with the mounting portion of the fixed side body by pushing the push-button against the mounting portion of the movable side body while a friction mechanism is provided for stopping the movable side body in a free stopping way when and after it reaches a predetermined opening angle, so that the movable side body is opened automatically to a predetermined angle relative to the fixed side body by pushing the push-button in a push style.
As the above-described conventionally known opening and closing device of a push type requires many parts and the structure thereof is complicated, there have been disadvantages that it often has trouble and is expensive.
An object of the present invention is to provide a small-sized opening and closing device suitable for use especially with a portable telephone which is so constructed to reduce cost by minimizing the number of parts to simplify the structure thereof, as well as to enable a push-button to be pushed lightly.
In order to achieve the above-mentioned object, the present invention is composed of a shaft, a slider cam attached to the shaft slidably in an axial direction, having a cam portion in one end portion thereof, a first compression spring interposed resiliently between the slider cam and the shaft, an inner cam attached rotatably relative to the shaft, having a cam portion provided on a side thereof facing the cam portion of the slider cam, an outer cam attached to the shaft with the inner cam accommodated rotatably therein and with a cam portion thereof facing the cam portion of the slider cam, a slide key attached non-rotatably and slidably in an axial direction relative to the outer cam, for arresting and releasing the inner cam, a push-button disposed in one end portion of the slide key, and a second compression spring with a weaker resilient force than that of the first compression spring, which is interposed resiliently between the push-button and/or the slide key and the outer cam, so that the length in an axial direction is shortened by having the inner cam for controlling the rotation of the slider cam, or the rotation of the shaft, accommodated inside the outer cam, and the push-button can be pushed lightly by using a coil spring for the push-button.
Here, the present invention can be so constructed to produce a state in which the inner cam is arrested by or released from the outer cam by providing on one side portion of the slide key an arresting leg portion having an arresting portion in a tip thereof, and by fitting the arresting portion slidably into a key groove disposed inside the outer cam while having the arresting portion fit into or removed from an arresting groove disposed in a flange portion provided in an outer circumference of the inner cam.
The present invention can also be so constructed to rotate the inner cam to return to its original position by providing a chamfered portion in the arresting portions of the slide key when the arresting portion is fit into the arresting groove of the inner cam due to the chamfered portion.
Furthermore, the present invention can be so constructed to fix the shaft engageably to a mounting hole disposed in a mounting portion of a movable side body, and fix the outer cam engageably to a mounting hole disposed in a mounting portion of a fixed side body.